Research methods for marine and estuarine fishes

Teleosts (fishes) and chondrichthyans (sharks, rays and chimaeras) comprise multiple and diverse taxonomic groups, which occur in freshwater, estuarine and marine ecosystems. These taxa can occupy three-dimensional space within a habitat, with some species inhabiting the deepest oceans. Therefore, undertaking research on these taxa often requires nuanced ethical and practical considerations, including specialised methods for capture or observation, and lethal research. This chapter reviews contemporary best practice methods for field-based research involving teleosts and chondrichthyans. The general operating procedures (GOPs) detailed in this chapter provide guidance around animal welfare considerations when undertaking research on these taxa, and are complementary to Chapters 30 (teleosts) and 31 (chondrichthyans). Researchers should use this chapter as a guide while drawing on their own knowledge and experience, and those of other experienced researchers to select the most appropriate methods for their study. This chapter is focused primarily on marine and estuarine species, but the sections on biological sampling, tagging, transport and housing may also apply to freshwater fishes (Chapter 32), or species that use freshwater environments for part of their life cycle. Marine and estuarine researchers may find that other GOPs within this book (including Chapter 14, which describes capturing, observing and handling freshwater animals, including fish) will also be relevant to their work, particularly if conducting research across freshwater and terrestrial landscapes.